Clutch Slave Cylinder
Fits:
Porsche 986 Boxster 2.5L / 2.7L 1997-99 (Chassis >>98XS603069)
This product supersedes Porsche's old part numbers:
- 98642337708
Click 'Zoom in' for large parts diagram.
Diagram ref no 14
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
98642337712
The product you are viewing cross references to these numbers
- Porsche Boxster 986 2.5L 1997-99
- Porsche Boxster 986 2.7L 1999-02
- Porsche Boxster 986 2.7L 2003-04

This product supersedes Porsche's old part numbers:
- 8E0 721 257 F
- 8E0 721 257 B
Fits:
Porsche 986 Boxster 1997-04
Porsche 987 Boxster 2005-08
Porsche 987C Cayman 2005-08
PLEASE NOTE:
For 986 Boxsters 2.5L / 2.7L 1997-99 upto chassis number WP0ZZZ98ZXS603069 you may require updated:
- pipe (No. 98642311325) CLICK HERE
and
- fitting bracket (No. 98642367725) CLICK HERE
A clutch that is engaged/disengaged via hydraulic fluid instead of a cable uses a Clutch Master and Clutch Slave Cylinder. When depressing the clutch pedal a lever is squeezed, forcing hydraulic fluid through hydraulic lines to a "slave cylinder" which houses a piston. The piston forces a push rod to engage or disengage the clutch. A clutch master cylinder that contains the hydraulic fluid sits on a support har near the clutch lever. When either the Master or Slave Cylinder fail the clutch is unable to be disengaged.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
8E0721257M
The product you are viewing cross references to these numbers
- Porsche Boxster 986 2.5L 1997-99
- Porsche Boxster 986 2.7L 1999-02
- Porsche Boxster 986 2.7L 2003-04
- Porsche Boxster 987 2.7L 2005 -08/08
- Porsche Cayman 2.7L 987C 2006-08

This product supersedes Porsche's old part numbers:
- 8E0 721 257 F
- 8E0 721 257 B
Fits:
Porsche 986 Boxster 1997-04
Porsche 987 Boxster 2005-08
Porsche 987C Cayman 2005-08
PLEASE NOTE:
For 986 Boxsters 2.5L / 2.7L 1997-99 upto chassis number WP0ZZZ98ZXS603069 you may require updated:
- pipe (No. 98642311325)
and
- fitting bracket (No. 98642367725)
A clutch that is engaged/disengaged via hydraulic fluid instead of a cable uses a Clutch Master and Clutch Slave Cylinder. When depressing the clutch pedal a lever is squeezed, forcing hydraulic fluid through hydraulic lines to a "slave cylinder" which houses a piston. The piston forces a push rod to engage or disengage the clutch. A clutch master cylinder that contains the hydraulic fluid sits on a support har near the clutch lever. When either the Master or Slave Cylinder fail the clutch is unable to be disengaged.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
8E0721257M
The product you are viewing cross references to these numbers
- Porsche Boxster 986 2.5L 1997-99
- Porsche Boxster 986 2.7L 1999-02
- Porsche Boxster 986 2.7L 2003-04
- Porsche Boxster 987 2.7L 2005 -08/08
- Porsche Cayman 2.7L 987C 2006-08
Porsche Clutch Slave Cylinders | Hydraulic Precision & Smooth Gear Engagement
The clutch slave cylinder is a vital component in your Porsche’s hydraulic clutch system. Working in tandem with the clutch master cylinder, it converts hydraulic pressure into mechanical movement to disengage the clutch, allowing smooth and precise gear changes. A properly functioning slave cylinder ensures a consistent clutch pedal feel and reliable performance on every drive.
At Design911, we supply premium clutch slave cylinders designed to meet or exceed original performance standards. Each component is precision-engineered using high-grade materials and corrosion-resistant seals to maintain hydraulic pressure, resist fluid leaks, and deliver smooth, consistent clutch engagement.
Whether you’re restoring a classic 911 or maintaining a modern Porsche sports car, our clutch slave cylinders ensure reliability, precision, and the performance your vehicle deserves.
What Does a Clutch Slave Cylinder Do?
The clutch slave cylinder is the final link in the hydraulic clutch system, responsible for actuating the clutch release mechanism.
Core Functions:
- Converts hydraulic pressure from the master cylinder into clutch release movement.
- Allows gear engagement and disengagement with minimal pedal effort.
- Maintains proper hydraulic pressure throughout the clutch system.
- Ensures consistent pedal feel and smooth shifting performance.
- Works in sync with clutch master and release bearing components.
Without a properly functioning slave cylinder, clutch engagement becomes inconsistent, leading to stiff or spongy pedal feel and difficulty shifting gears.
Why Do Clutch Slave Cylinders Fail or Degrade?
Clutch slave cylinders operate under high hydraulic pressure and are exposed to heat, vibration, and clutch dust — all of which can cause wear and failure over time.
Common Causes of Failure Include:
- Internal seal wear causing fluid leaks.
- Air ingress into the hydraulic system.
- Corrosion from moisture-contaminated brake fluid.
- Cracked housing due to mechanical stress or age.
- Fluid contamination leading to seal deterioration.
When a slave cylinder fails, you may notice clutch fluid leaks, a soft or sinking pedal, or complete clutch disengagement failure.
Why Replace or Upgrade Your Porsche Clutch Slave Cylinder?
Replacing a worn or leaking clutch slave cylinder restores proper hydraulic performance, consistent clutch engagement, and pedal response.
Key Benefits:
- Restores smooth, responsive clutch operation.
- Prevents fluid leaks and loss of hydraulic pressure.
- Improves gear shift accuracy and driver control.
- Ensures long-lasting reliability and performance.
- Compatible with Porsche 911, Boxster, Cayman, and other models.
- Ideal for routine maintenance, clutch upgrades, or complete hydraulic rebuilds.
For optimal performance, it’s recommended to replace both the master and slave cylinders together to maintain system balance and pressure consistency.
Highlights
- Precision-engineered Porsche clutch slave cylinders.
- High-quality seals and durable construction for reliability.
- Consistent hydraulic pressure and pedal feel.
- Direct-fit replacements for modern and classic Porsche models.
- Resistant to heat, corrosion, and clutch fluid degradation.
- Perfect for maintenance, performance upgrades, or restorations.